According to one prior art method of issuing an instructional signal to a selected one of the cars making up a train, a signal having a specific frequency is allocated to each car of the train; each car is equipped with a receiver which receives only the specific frequency signal allocated thereto; and an instructional signal at said specific frequency is transmitted to the selected car, thereby issuing an order to the car. According to another method, in which a basic condition is that a car maintains a fixed position in the train, an order line runs from the dispatcher car to a car to be sent an instructional signal and over this line an instructional signal is sent to the desired car.
In the former method, each car has to be equipped with a receiver which can receive only its specific assigned frequency signal; and, accordingly, when a train is composed of many cars, the installation and maintenance costs involved will be so high that it is practically impossible to adopt this method.
The latter method, which is based on the maintainance of the position of each car in a train, is virtually impossible to use for a train which is subjected very often to makeup, breakup, and directional change.
In view of these disadvantages of the conventional methods, the primary object of the present invention is to provide a system for issuing instructional signals to individual cars of a train which is often subjected to makeup, breakup or directional change, and by which system an instructional signal can be issued to any car in a newly madeup train, regardless of any change in the number of cars in the train, the direction of travel of the train, and the relative position of the car in the train.
Another object of the present invention is to provide an economical system for issuing instructional signals to individual cars of a train, especially one containing a large number of cars, with which system there is no need of equipping each car of the train with a receiver which receives a specific frequency signal allocated thereto; and, accordingly, the installation and maintenance costs can be greatly reduced.